Although taking a few months longer than expected, Automattic and the volunteer developers have finally released version 3.4 of the widely used WordPress blogging platform.

Users who upgrade to the new edition will enjoy such features as the ability to test themes before applying them to the entire blog site and the ability to add HTML code to their photo captions.

WordPress is the most widely used blogging platform, deployed for almost half the world's blogs, according to a recent estimate by Pingdom, a Web services firm. The developers had planned to release new versions of the open source software every three or four months. Version 3.4, however, is the first major release since last December, when version 3.3 was released.

The biggest addition to this version is a new theme customizer, according to WordPress cofounder Matt Mullenweg, who explained the new features in a blog post. A theme is a third-party free or paid style template that can be placed over the WordPress site, giving the text and layout a customized look. This feature allows you to view new themes in a test mode before publishing them. It also radically eases the process of selecting backgrounds and images.

"The theme customizer ... allows you to play around with various looks and settings for your current theme or one you're thinking about switching to without publishing those changes to the whole world," Mullenweg wrote. "For themes that support it, you can change colors, backgrounds, and of course, custom image headers."

"WordPress hasn't historically handled rich media and other digital assets in an intuitive way," so the theme customizer and related features is something "many users will appreciate," Irina Guseva, an analyst for The Real Story Group, said in an e-mail.

Also noteworthy is the ability to add HTML code to image captions, allowing users to stylistically format parts of the captions and add links. Other new featuresinclude the software's new ability to recognize links to individual Twitter messages. Links to individual messages are automatically converted into fully formatted Twitter messages on the page. Various bug fixes, performance improvements, and developer optimizations have been added as well. The development team will add more functionality to the customizer in future editions.

Potential users can deploy either a version hosted by Automattic or by other hosts, or download a copy to run on their own servers. Current users can get the new version via the upgrade button that will appear on their administrative console.

Following its tradition of naming its releases after jazz musicians, WordPress 3.4 has been named after guitarist Grant Green.